ImportError：无法导入名称main。为什么我不能下载jupyter？

Question

我无法下载jupyter笔记本。

class RecordingClientEngine: ClientEngine {
    var requests: [String] = []
    func request(_ request: String) -> Void {
        requests.append(request)
        print("recording: \(request)")
    }
}

let client = Client<ProfilesAPI>(engine: RecordingClientEngine())